Daniel Irimia is a bioengineer, a medical doctor by training, and a researcher in the areas of microfluidics, inflammation, and sepsis. He is an Associate Professor in the Surgery Department at Massachusetts General Hospital (MGH), Shriners Burns Hospital, and Harvard Medical School. He is a leader in the design of novel tools for measuring human neutrophil activities in health and disease. He was recently awarded the "Pioneers of Miniaturization" prize from the Chemical and Biological Microsystems Society for his work on microfluidic tools for analyzing neutrophils and other leukocytes.

Autocatalytic Immune Reactions

Neutrophil swarms protect healthy tissues by sealing off sites of infection. During swarming, neutrophils accumulate fast and in large numbers, under the control of mediators released by neutrophils already at the site. These mediators stimulate the arrival of additional neutrophils in an autocatalytic reaction that results in an exponential rate of swarm size increase. However, despite the autocatalytic reaction, not all 25 billion neutrophils from one’s body end up in one giant swarm. Thus, our recent goal was to identify the physiologic mediators that disrupt the autocatalytic reaction and stop the growth of neutrophil swarms. For this, we developed and validated large microscale arrays of microbe clusters, which can trigger the synchronized growth of thousands of swarms at once. The new tool enabled us to concentrate large amounts of swarm-released mediators in small volumes, and ultimately identify lipoxin A4 (LXA4) is a key mediator that disrupts the autocatalytic reactions, stops the growth of swarms, and ultimately leads to swarm dispersal. These and other insights from the study of neutrophil swarming will teach us how to design better strategies to combat infections and to control acute and chronic inflammatory diseases.